Back gauge warning system for shears and the like

ABSTRACT

A safety warning system for use with a shear or the like is disclosed wherein a light beam source and photosensor means are mounted beneath the movable cutter knife and back gauge assembly of the shear to detect the stack up of sheared stock and effect a signal to the operator when a predetermined stack height is reached so that the sheared portions may be removed from the receiving area or the shear stopped to prevent the back gauge from striking the stacked stock with resulting damage to the back gauge.

United States Patent [191 Roberts 1 Dec. 16, 1975 BACK GAUGE WARNING SYSTEM FOR SHEARS AND THE LIKE Inventor: Verne W. Roberts, 5021 Glendale Drive, Gumee, 111. 60031 Filed: Dec. 9, 1974 Appl. No.: 530,722

US. Cl. 83/96; 233/61; 831/167; 83/268; 83/358; 83/395; 83/522 Int. Cl. B26D 7/16; B26D 7/22 Field of Search 83/96, 167, 268, 358, 395, 83/522, 79, 61, 94, 212; 214/1.6

References Cited UNITED STATES PATENTS 2,071,402 2/1937 Hazelton 83/395 11/1940 Van Dusen 83/395 2,310,182 2/1943 Munschauer 83/395 Primary Examiner-Frank T. Yost Attorney, Agent, or FirmFitch, Even, Tabin & Luedeka [57] ABSTRACT 5 Claims, 4 Drawing Figures US. Patent Dec.16,1975 Sheet10f2 3,926,081

[ US. Patent Dec. 16,1975 Sheet20f2 3,926,081

BACK GAUGE WARNING SYSTEM FOR SHEARS AND THE LIKE has reached a height at which the stack could be en- 1 gaged by the back gauge of the shear with resulting damage to the back gauge.

Conventional shears include base frames which have laterally spaced generally upstanding end plates. The end plates support a horizontal support table along with sheet stock to be sheared may be moved into position to underlie a cutter knife or shear blade. A back gauge is generally provided rearwardly of the cutter knife and serves as a stop against which the sheet stock may be positioned to establish aa predetermined size of the sheet stock to be sheared. The back gauge is vertically movable with the shear knife and always extends below the cutting edge of the shear knife. As the sheet stock is sheared, the sheared portions drop into a receiving area between the end plates and below the shear knife and back gauge to form a stack of sheared pieces. As the height of the stacked sheared pieces increases, it reaches a height at which, if the sheared portions are not removed, the back gauge may strike the stack which results in severe damage to the back gauge.

The present invention provides a safety warning system for such a shear which signals the operator when the stack of the severed pieces reaches a predetermined height so as to allow the operator to stop the shear or otherwise reduce the stack sufficiently to prevent the back gauge from striking the stack of sheared pieces, and thereby prevent damage to the back gauge..

Alternatively, the safety system in accordance with the present invention may be employed to automatically stop the shear before the stack of sheared workpieces reaches a height which could damage the back gauge.

Accordingly, one of the primary objects of the present invention is to provide a novel safety warning system for use with a shear and the like, which system is operative to signal an operator prior to a stack of sheared workpieces reaching a height which could result in damage to the back gauge of the shear.-

Another object of the present invention is to provide a novel warning system for a shear and the like wherein photosensor means are positioned adjacent a sheared workpiece receiving area of the shear and are connected in circuit to warning signal means so as to provide a warning to an operator when the stack of sheared workpieces reaches a predetermined height above which damage to the back gauge of the shear could result.

Further objects and advantages of the present invention, together with the organization and manner of operation thereof, will become apparent from the following detailed description of the invention when taken in conjunction with the accompanying drawings wherein like reference numerals designate like elements throughout the several views, and wherein:

FIG. 1 is a perspective view of a shear employing a safety warning system in accordance with the present invention, portions of the shear being broken away and a number of severed sheets being shown stacked between the end plates of the shear after shearing;

FIG. 2 is a somewhat schematic sectional view, taken generally transverse to the longitudinal axis of the shear of FIG. 1, illustrating the manner in which sheet stock is sheared and stacked between the end plates of the shear;

FIG. 3 is a schematic circuit diagram of the safety warning system in accordance with the present invention; and

FIG. 4 is a circuit diagram showing the receiver connected in circuit with the various warning system indicators.

Referring now to the drawings, and in particular to FIG. 1, a shear employing a safety warning system in accordance with the present invention is indicated generally at 10. The shear 10, to be briefly described hereinafter, is illustrative of but one type of shear or the like with which the safety warning system in accordance with the present invention may be employed. The shear 10 includes frame means, indicated generally at 12, having a pair of laterally spaced generally identical upstanding end plates 14 and 16 which rest upon the floor or support surface underlying the shear 10. A horizontally disposed support table 18 is supported by the end plates 14 and 16 and has an upper support or guide surface 20 upon which metallic sheet stock 21 (FIG. 2) may be positioned preparatory to shearing the sheet into smaller pieces of predetermined size.

The support table 18 has a stationary knife or shear block 22 secured thereon at the rearward upper edge of the support table, the shear block 22 having its upper surface coplanar with the guide surface 20. In the embodiment of the shear 10 illustrated in FIG. 1, extension support arms, one of which is indicated at 24, are mounted on the support table 18 in a conventional manner to provide additional support for the sheet stock 21 as it is introduced into the shear 10 for shearmg.

With particular reference to FIG. 2, the shear 10 includes a movable shear knife or blade 28 which is supported between the end plates 14 and 16 for movement in a generally vertical direction in a known manner. The movable shear knife 28 has a shearing block 30 secured to the forward lower edge of the movable knife adjacent a lower end surface 32 thereof. The shearing block 30 defines a shearing edge which is cooperative with the stationary shear block 22 to effect shearing of the sheet stock 21. To this end, the movable knife 28 is movable between an upper position, wherein the shearing block 30 is spaced above the plane of the upper guide surface 20 of the support block 18, and a position wherein the shearing block 30 passes downwardly through the plane of the upper support surface 20 during a shearing operation, as is known.

The shear 10 includes a back gauge assembly, indicated generally at 36, which is of known construction and is movable with the movable shearing'knife 28 between its upper and lower positions. The back gauge assembly 36 includes an inverted L-shaped stop member 38 which is secured to the bottom surfaces of a pair of laterally spaced identical support blocks, one of which is shown at 40. As is known, the support blocks 40 are supported by and adjustably movable longitudinally along the lengths of associated guide bars 42 by means of screw shafts, one of which is shown at 44. Means (not shown) are provided for rotating the screw shafts 44 to effect selective movement of the support blocks 40 and associated stop member 38 along the lengths of the guide bars 42. In this manner, the stop member 38 may be moved to a selected position relative to the cutting plane defined by the shear blocks 22 and 30 so as to establish a predetermined length of sheet stock which will be sheared from the sheet 21 when the inner edge of the sheet is positioned against the stop 38 during a shearing operation. The guide bars 42 and associated support blocks 40 and stop member 38 are secured in rigid relation to the movable knife 28 through suitable attaching bracket means 46.

During a shearing operation, a piece of sheet stock 21 is placed on the support surface of the support table 18 and is moved to a position wherein its inner end abuts the stop member 38 which has previously been adjusted to establish a predetermined width of sheet stock to be sheared. The shear 10 includes drive mechanism, indicated generally at 50 in FIG. 1, of known design which is operatively associated with the movable shear knife 28 to effect downward movement thereof to a shearing position through the operation of a foot pedal actuator 52 by the operator of the shear. The drive mechanism means 50 is operative to effect downward movement of the movable shear knife 28 to a position wherein the shear block cooperates with the stationary shear block 22 to shear the sheet stock 21. As the sheet stock 21 is sheared, the severed sheet portion, such as indicated at 21a in FIGS. 1 and 2, will drop down into a receiving area defined between the laterally spaced upstanding end plates 14 and 16 of the shear 10.

To assist in generally uniform positioning and stacking of the severed workpiece portions 21a, a generally vertically disposed guide plate 54 is secured in depending normal relation to the support block 18 and provides a guide surface for the adjacent forward edges of the sheared workpieces. It will be understood that the operator may continue to feed sheets of stock 21 into the shear 10 to shear a plurality of pieces 212 which will drop downwardly into the receiving area defined between the end plates of the shear 10 in stacked relation with preceding sheared workpiece portions to provide a stack of sheared workpieces.

To facilitate operation of the shear 10, a plurality of hold-down members 56 are provided along the transverse width of the shear 10 to engage the sheet stock 21 above the stationary shear block 22 as the movable shear knife 28 is moved downwardly to shear the sheet stock. Each of the hold-down members 56 is of conventional known design and may include a generally cylindrical pressure foot 58 which may be slightly resiliently biased outwardly from an associated cylinder 60, the lower end of each cylindrical pressure foot 58 being disposed below the lower surface 32 of the movable knife 28 so that the pressure feet 58 engage the sheet stock 21 prior to shearing. The hold-down members 56 may be carried by the movable shearing knife 28 as through attaching brackets 62 (FIG. 2).

It will be seen from FIG. 2 that the lowermost edge of the stop member 38 is disposed below the lower surface 32 of the movable knife 28 and will therefore always be disposed below the shearing edge defined by the movable shear block 30 during movement of the shearing knife 28. It has been found that when the sheared workpieces 2la drop down into the receiving area between the end plates 14 and 16 of the shear 10, they do not always stack uniformly; that is, the forward edges of the severed stacked pieces do not always abut the plate 54, with the result that the rear edges of some of the 4 stacked pieces may extend rearwardly beyond a vertical plane vertically aligned with the stop member 38. As a result, if the stack of sheared workpieces 21a is allowed to become too high, the stop member 38 may engage the stack during downward movement of the back gauge assembly 36 with resulting damage to the stop member 38 and associated back gauge assembly.

The present invention is concerned with providing a safety warning system which is operative to provide a visual and/or audible signal to the operator when the height of the stacked sheared workpieces 21a reaches a predetermined height which is safely below the lowermost position of movement of the stop member 38 during a shearing operation. To this end, the safety warning system in accordance with the present invention includes light source means, indicated generally at 66, supported by the frame means 12 and adapted to project a light beam between the spaced end plates 14 and 16 through the receiving area which receives the severed workpieces 21a. In the illustrated embodiment, the light source means 66 includes a conventional electric eye 68 which is suitably mounted on the end plate 14 adjacent a recessed throat area 70 formed in the end plate 14. The electric eye 68 is mounted adjacent a suitable opening (not shown) in the end plate 14 so as to project a light beam across the area defined between the spaced end plates 14 and 16 of the frame means 12.

Light receiver means of conventional design, indicated generally at 74, are mounted on the end plate 16 in alignment with the light beam produced by the electric eye 68 so as to receive the light beam projected by the electric eye when the light path between the end plates 14 and 16 is unobstructed. To this end, the light receiver means 74, which might alternatively be defined as photosensor means, is mounted outwardly of the end plate 16 with its photocell lens adjacent an opening through the end plate 16. It can be seen that with the electric eye 68 and associated light receiver 74 mounted as described to project and detect a light beam across the receiving area defined between the spaced end plates 14 and 16 of the shear 10, and by positioning the electric eye 68 and light receiver 74 at a predetermined height above the floor surface upon which the shear 10 is supported, means are provided to detect an obstruction of the projected light beam at a predetermined height above the floor surface.

With particular reference to FIGS. 3 and 4, the light source means 66 and light receiver 74 are connected in circuit with a visual indicator and an audible signal producing device to produce signals to the operator of the shear 10 when the stack of sheared workpieces 21a reaches a predetermined height so that the operator can remove the sheared workpieces 212 before the stack reaches a height at which it could be engaged by the stop member 38 of the back gauge assembly 36 during a shearing cycle with resulting damage to the back gauge assembly. An indicator or signal light 76, which preferably comprises a conventional red light and is mounted on the forward upper portion of the shear 10 as shown in FIG. 1, and a conventional audible sound device 78, such as a conventional bell, are connected in parallel with the receiver 74 between ground and a 120 volt AC. voltage source, indicated at 80. The voltage source may comprise the power supply for the main drive motor of the shear. A single pole, double throw, key-operated selector switch 82 of conventional design is connected between the power source 80 and the remainder of the warning circuit, as shown in FIG. 3, to allow selective enabling or disabling of the warning system. A conventional on-off switch 84 is connected in series with the bell 78 to allow selective connection of the bell in circuit for enabling or disabling the bell 78 as a signal producing means. A white light 86 is connected in parallel with the light source 66 and the receiver 74 and provides an indication of whether the warning signal circuit of FIG. 3 is connected to the voltage source 80 through the switch 82. The light 86 and bell 78 are also preferably mounted on the upper forward portion of the shear 10.

The receiver 74 is of conventional design and includes a built-in time delay so that momentary interruption of the light beam received from the light source 66, as during dropping of sheared pieces 21a onto the stack between the end plates 14 and 16, will not produce a signal such as desired when the stack reaches a height to endanger the back gauge. FIG. 4 schematically illustrates the receiver 74 and its relay contacts which include a pair of normally closed contacts 74a, a pair of normally open contacts 74b, a pair of normally open contacts 74c, and a pair of normally closed contacts 74d. The pairs of relay contacts 74a-d are disposed in their normal positions when the receiver 74 receives or detects a light beam from the light source 66. The receiver 74 is connected to the power supply 80 and ground through contact terminals 74e and 74f. It will be noted that the indicator light 76 and bell 78 are connected to the negative or ground polarity of the relay of the receiver 74. This prevents damage to the relay of the receiver 74 if the light 76 or bell 78 should short out. As shown in FIG. 4, conductors 88 and 90 are connected to the pair of relay contacts 74d. The conductors 88 and 90 may be connected to the control circuit (not shown) for the shear such that interruption of the light beam to the receiver 74 for a period of time in excess of the built-in time delay of receiver 74 will deactivate the shear 10, as well as cause the alarm bell 78 and red light 76 to be energized. The conductors 88 and 90 may be used for other functions in connection with operation of the shear 10 as desired. To this end, a by-pass switch 92 may be connected between the conductors 88 and 9.0 to bypass the relay contacts 74d.

The warning circuit, as shown in FIG. 3 and including the light source 68 and receiver 74, is operative to maintain the circuit through the light 76 and bell 78 is an open condition when the light beam from the source 68 is received by the receiver 74. When the stack of sheared workpieces 21a reaches a predetermined height so as to interrupt the light beam from the electric eye 68 to the receiver 74 for a predetermined time period as established by the built-in time delay of the receiver, the normally open relay contacts 74b of the receiver 74 are closed to energize the light 76 and alarm bell 78, assuming switch 84 to be closed, whereby to provide both visual and audible signals to the operator indicating that pieces should be removed from the stack 21a to prevent the back gauge stop 38 from striking the stack of sheared pieces with possible damage to the back gauge.

Thus, in accordance with the present invention, a back gauge warning safety system for a shear or the like is provided which warns the operator when the stack of sheared workpieces reaches a height at which it would cause damage to the back gauge of the shear. The operator can then reduce the stack sufficiently to pre- 6 vent damage to the shear l0 and preclude possible endangerment of the operator.

While a preferred embodiment of the invention has been illustrated and described, it will be obvious to those skilled in the art that changes and modifications may be made therein without departing from the invention in its broader aspects. For example, the receiver 74 may alternatively comprise a light reflector, with the light source means 66 having means responsive to light reflected by the reflector from the light source means 66 to effect energizing of light 76 and bell 78 when the light path is interrupted. The light receiver 74 is preferred because it is less susceptible to coating with oil or other contaminants during operation of the shear 10.

Various features of the invention are defined in the following claims.

What is claimed is:

1. In a shear or the like having frame means, means defining a generally horizontal support surface along which a workpiece may be moved preparatory to shearing the workpiece, cutter means supported by said frame means and having a cutting edge movable between a first position spaced above the plane of said support surface and a second position spaced below the plane of said support surface so as to shear a workpiece underlying said cutting edge when moved from its said first to its said second positions, back gauge means disposed rearwardly of said cutter means and movable with said cutting edge, said back gauge means being disposed to provide a stop against which the leading edge of a workpiece may abut to establish a predetermined length of the workpiece to be sheared by said cutting edge, said frame means defining a receiving area below said cutter means and said back gauge means to receive severed portions of workpieces which may progressively stack up, and drive means operative to effect selective movement of said cutter means and back gauge means between their said first and second positions; the combination therewith comprising safety means operatively associated with said frame means and adapted to detect the presence of stacked severed workpiece portions at a predetermined height in said receiving area below said cutter means and said back gauge means, said safety means including means for providing a signal when the stack of severed workpiece portions in said receiving area reaches said predetermined height such that an operator is notified to remove severed workpiece portions from below said cutting means and back gauge means before said stack reaches a height sufficient to be engaged by said back gauge means.

2. The combination as defined in claim 1 wherein said frame means includes a pair of laterally spaced upstanding end plates which define said receiving area therebetween, and wherein said safety means includes light source means adapted to project a light beam across said receiving area at a predetermined position relative to the path of travel of said back gauge means, and photosensor means adapted to detect the passage of said light beam across said receiving area, said light source means and said photosensor means being in circuit with said signal means to provide said signal when the stack of severed workpiece portions within said receiving area reaches a predetermined height.

3. The combination as defined in claim 1 wherein said means for providing a signal comprises a visually observable light.

7 8 4. The combination as defined in claim 2 wherein pieces. said safety means includes an audible sound producing 5. The combination of claim 1 wherein said means means connected in circuit with said photosensor for providing a signal includes both audible sound promeans and operative to produce an audible signal when ducing means and a visual indicator. said light beam is interrupted by stacked severed work 

1. In a shear or the like having frame means, means defining a generally horizontal support surface along which a workpiece may be moved preparatory to shearing the workpiece, cutter means supported by said frame means and having a cutting edge movable between a first position spaced above the plane of said support surface and a second position spaced below the plane of said support surface so as to shear a workpiece underlying said cutting edge when moved from its said first to its said second positions, back gauge means disposed rearwardly of said cutter means and movable with said cutting edge, said back gauge means being disposed to provide a stop against which the leading edge of a workpiece may abut to establish a predetermined length of the workpiece to be sheared by said cutting edge, said frame means defining a receiving area below said cutter means and said back gauge means to receive severed portions of workpieces which may progressively stack up, and drive means operative to effect selective movement of said cutter means and back gauge means between their said first and second positions; the combination therewith comprising safety means operatively associated with said frame means and adapted to detect the presence of stacked severed workpiece portions at a predetermined height in said receiving area below said cutter means and said back gauge means, said safety means including means for providing a signal when the stack of severed workpiece portions in said receiving area reaches said predetermined height such that an operator is notified to remove severed workpiece portions from below said cutting means and back gauge means before said stack reaches a height sufficient to be engaged by said back gauge means.
 2. The combination as defined in claim 1 wherein said frame means includes a pair of laterally spaced upstanding end plates which define said receiving area therebetween, and wherein said safety means includes light source means adapted to project a light beam across said receiving area at a predetermined position relative to the path of travel of said back gauge means, and photosensor means adapted to detect the passage of said light beam across said receiving area, said light source means and said photosensor means being in circuit with said signal means to provide said signal when the stack of severed workpiece portions within said receiving area reaches a predetermined height.
 3. The combination as defined in claim 1 wherein said means for providing a signal comprises a visually observable light.
 4. The combination as defined in claim 2 wherein said safety means includes an audible sound producing means connected in circuit with said photosensor means and operative to produce an audible signal when said light beam is interrupted by stacked severed workpieces.
 5. The combination of claim 1 wherein said means for providing a signal includes both audible sound producing means and a visual indicator. 